Many individuals do not like conflict and their definition of conflict is anything that might cause individual or group discomfort. So there is subtle pressure put on board members to be nice and not rock the boat by naming issues that are out there and need discussion. (The same dynamics can be had on almost any team.)
I recently read an article about Patrick Lencioni suggesting that one of the reasons that major financial institutions have found themselves in so much trouble recently is the prevailing culture on company governance boards to not deal with issues that would make others uncomfortable. So the culture of nice sabotages a culture of truth and effectiveness.
Pastors, leaders, board members or team members who choose not to speak in the face of real unspoken issues do a disservice to the organization they serve. The irony is that everyone generally knows that there are unspoken issues - they just don't want the discomfort of naming them.
Now how we speak to the issues is important. If I approach an unspoken issue and put it on the table it will be best received if: There is not a personal vendetta; my words are not meant to hurt; I don't have a hidden personal agenda; I want the best for the organization; I communicate in a way that invites rather than dis invites dialogue; I say it in love; and I acknowledge that the issue may make others uncomfortable.
The funny thing about "elephants" is that once they are named they are no longer elephants. I once worked with a group around a whiteboard and asked them to name every elephant they felt existed in their organization. We willed the white board (a bad thing) but once up there we could talk about all of them (a good thing). Once named an elephant is simply another issue that we are allowed to talk about. Unnamed it is one of the unspoken discussions that we know we need to have but don't have the courage to discuss.
Every board, team and organization is better off with a high level of candor coupled with a high level of trust which mitigates against the candor turning into anger or cynicism.
If you are brave, I would suggest that you ask your team or your board in a relaxed atmosphere to brainstorm on any unspoken board discussions you need to have, on any elephants that need to be named, white board them and then develop a plan to talk through them one by one.
Unspoken discussions are not discussions, just frustrations and they often hide real issues that unresolved will hurt the organization.